In a food processor combine cream cheese, yogurt, SweetN Low®, and vanilla and process until smooth. Transfer to a bowl, cover, and chill. Thread blueberries onto 8 skewers, leaving 1 of bare skewer at the pointed end. Use a small star-shaped cookie cutter to cut out watermelon. Place 1 watermelon star at the end of each skewer. Take cheesecake dip out of refrigerator 30 minutes before serving.